iPerf uses a default of 1Mb/sec for UDP tests. Use the -b flag on the iperf client to specify the UDP bandwidth you want to transmit at e.g.

I confirmed the change with an app on my phone to the server. Using the default client settings, I saw 1.05 Mbps. I changed the client argument to -b 100M and I got 94 Mbps throughput. Additionally I tested -b 10M and verified that I saw 9.96 Mbps. To be on the safe side i also upgraded my iperf version on the server to 2.0.10.